


The Case of the Louisiana Lake

by Bitenomnom



Category: Sherlock (TV)
Genre: (sort of), Based on a song, Crossover, Drugs, Friendship, Gen, Lake Pontchartrain, Ludo - Freeform, Sherlock and John go abroad, casefic
Language: English
Status: Completed
Published: 2012-10-31
Updated: 2012-10-31
Packaged: 2017-11-17 10:58:54
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 5,989
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/550818
Author URL: https://archiveofourown.org/users/Bitenomnom/pseuds/Bitenomnom
Summary: <blockquote class="userstuff">
              <p>A young man from the U.S. charged with the murder of his two friends implores Sherlock and John to investigate his case and prove his innocence. But…there isn’t <i>really</i> such a thing as a lake that eats people, is there?</p>
            </blockquote>





	The Case of the Louisiana Lake

**Author's Note:**

> ** Before you read this, listen to [this song](http://youtu.be/n-BRKoNNMJQ) ("Lake Pontchartrain" by Ludo). It serves as the suspect's statement to the police in this story! **
> 
> I hope this isn't too boring. XD I don't know why I thought it would be a good idea for me to try to write something scary, especially something with so much plot to cover. I was torn between two possible directions (more supernatural vs. more scientifically explicable), so I hope my having opted for one over the other isn't too much of a disappointment/surprise/whatever. 
> 
> Hope you enjoy it (and happy Halloween)!

            “Right, but,” John said as they boarded the aeroplane, “really, you’re just taking this case to get away from Mycroft or something, aren’t you?”

            Sherlock shrugged his bag off of his shoulder. “That is one significant advantage.”

            John paused to stare at him in disbelief. “But not the _only_ reason, is what you’re saying. Sherlock, you—you don’t _honestly_ think he’s innocent, do you?” John sighed and rolled his eyes as Sherlock shoved past him for the window seat. “I mean, forgive me for saying it, but isn’t it a bit _obvious_?”

            “I’d be interested in your analysis.”

            “He killed his friends and dumped their bodies in the lake,” John said. “Came up with a fanciful story to tell the police, which they rightly realized was shit. You heard the police recording of his version of the events, for god’s sake; at least I hope you actually listened, since he bothered to send it to you.”

            “Yes, exactly,” Sherlock said, and lowered his voice to a whisper when he got dirty looks for talking over the safety demonstration. “The suspect sent us that recording himself. If it were damningly false, why bother?”

            “He thinks he’s a really convincing storyteller?” John suggested.

            “Yes, after the police failed to be convinced he thought he’d just pass it on to _me_ in the hopes I could be convinced when they weren’t.”

            “Well, you are, aren’t you?”

            Sherlock shook his head. “Whatever actually happened—which I suspect we will discover soon enough—Burroughs believes his tale to be the truth. Why he would have gone to the police and reported the incident, thereby clueing them in to where to search for the bodies, if he had done what you suggest?”

            “True enough,” John sighed. “Well, he could have been on some sort of drug, or something, and didn’t realize he was the one who did it,” John said. “Crazier things have happened than people murdering their friends while high.”

            “Possible,” Sherlock acknowledged. “Until you consider that there were no signs of drug usage in his blood or urine.”

            “Unless it had already passed through.”

            “Until we can gather the facts, there are a hundred possible explanations. I suggest you focus on getting an appropriate amount of rest so we can start straight away once we arrive in New Orleans.”

 

 

 

            The authorities’ cooperation was limited—naturally—and so what they were left with was the surviving friend’s explanation.

            “God,” John groaned as they climbed into the vehicle after leaving the police station. “I hate jet lag.”  
            “Mm,” Sherlock said.

            “You sure you’re okay to drive?”

            “I’ve a license from when I was in Florida years ago,” Sherlock said, “making sure Mrs. Hudson’s husband was appropriately convicted. Oh—you mean my current physical state. Yes, fine; I shan’t be requiring sleep for some time.”

            John supposed that was good enough; anyway, Sherlock was the one raring to go.

            “We should take the same path they did,” Sherlock said idly as he waited for John to buckle in.

            “They started in Missouri,” John pointed out. “That’s _hours_ away.”

            “Good job I’m not as tired as you are, then.”

            “I figured you’d find driving _boring_.”

            Sherlock shrugged. “No less boring than anything else, I assure you. Besides, I can analyze the data along the way.”

            “Look, here’s the thing—all the main points in the kid’s story point to areas around here, by the lake itself.” He nodded toward the map unfolded on the dashboard. “If we can find that restaurant Burroughs mentioned, that seems like the first important thing besides their starting location. And if we need to go back further later, we can.” Sherlock was clearly unconvinced. “Sherlock, I don’t want to be stuck in the car long enough to discover that after the sixth hour you go to your mind palace whilst driving, all right? And don’t—” he held up a hand, “correct me on that one.”

            “Then I shall leave you to your delusions.”

            John sighed. “So the restaurant is, what, maybe two hours away at most? He said it was in Louisiana.” John squinted at the map. “Right, so that’s a pretty small range, compared to the whole trip anyway. We could start there. It’d save us about twenty hours of driving in total, Sherlock.” He glanced up; Sherlock was looking coolly out the windshield at the police station. “Come _on._ If we need to go to Missouri later, we can. But maybe all the answers are close—well, _closer_ —by.”

            “Fine,” Sherlock huffed. “We’ll find the restaurant first.”

 

 

           

            Sherlock, as it turned out, talked the entire way to the restaurant, but John’s lack of sleep was catching up to him, so all he caught were intermittent mentions of, “…couldn’t possibly have been hypnosis…” and “…should be obvious once we follow the route…” and “…and ever since then Mycroft refuses to eat shellfish…” (which John, admittedly, wished he had been awake to hear—), “…and we had to hire a crew to clean the furniture…” (then again, maybe not). Just as he was finally able to start drifting off, they were at the restaurant on the side of the highway.

            “This must be it,” Sherlock said, leaping out with, in John’s opinion, far too much vigor for someone who got as little sleep as he did.

            “You’re awfully interested in this,” John moaned, climbing out. “Could you, I dunno, tone it down a few notches? What’s got in your head?”

            “Do you remember last time someone came to us with an unbelievably likely story about someone close to him being killed by supernatural forces?”

            “Yeah. As I recall, you drugged me.”

            The mention of it only slowed Sherlock down for a moment. “Yes, but it was so _interesting_.”

            “So you think that this is—what—somebody trying to cover something else up?” he asked as they entered.

            “It’s not impossible. Perhaps these individuals were only one piece of a larger scheme.”

            John rolled his eyes. “Right. Well. I can see you don’t subscribe to Occam’s Razor.”

            Sherlock smirked.

            “What?”

            “Nothing.”

            “Seriously, Sherlock,” John said as they neared the place, some homely hole-in-the-wall boasting freshly caught shrimp and homegrown grains and vegetables, but mostly boasting chipped paint and rickety shutters. “What?”

            “You don’t usually push back this much. Are you that confident in your theory, or just feeling particularly stubborn today?” (Because it was, of course, god, still _today_ , bloody time change.)

            “Oh, right, sorry, I’ll just shut up and let you make an arse of yourself on your own,” John crossed his arms.

            “No, by all means, continue. It’s…nice.” Before John could think of anything to say in response to _that_ , Sherlock had maneuvered them to a small table inside the place. The inside was marginally cleaner than the outside, but certainly no less worn. The only other patron gave them a strange look between bites of what appeared to be shrimp, and then gave them a longer strange look, and then apparently couldn’t look away, and John sighed. It seemed London wasn’t the only place everyone assumed they were a couple.

            “How can I help you boys?” a squat waitress ambled up to them, giving them a similar evaluative look before making a visibly conscious decision not to think any further on the matter. John supposed it wasn’t altogether unsurprising; Sherlock had picked the smallest table. Their knees were almost touching, with Sherlock’s ungodly long legs.

            “The two others got crawfish, and the accused got chicken,” Sherlock said to John, as if the waitress weren’t there, staring at the menu with what may as well have been intent to memorize its contents to the letter. For the waitress’ part, she seemed to be smitten with their accents, or at least with Sherlock himself, and paused indecisively between reasserting her presence and simply waiting it out.

            “You get what you want, but you are _not_ experimenting on me again,” John said, and tried to ignore the bug-eyed expression of the waitress.

            “I suppose you’rethe doctor; best if anything happens, it happens to me.” He folded his hands and concentrated inward. “I oughtn’t have both, could confuse things more if one or the other had some sort of an effect…Burroughs did seem rather hung up on the crawfish…”

            John gave the waitress a sympathetic look and glimpsed at his menu one more time. “I’ll have the reuben,” he finally decided.

            “Crawfish for me,” Sherlock said.

            The waitress nodded. “All right.” She paused. “What brings you boys around here, anyway? Visiting somebody?”

            “Investigating a murder,” Sherlock said brightly, and John buried his face in his hands.

            “Don’t mind him,” John said. “He’s slightly mental.” The waitress tittered. “We’re just on a bit of a, er, road trip.”

            “I’ll tell you what, you oughtta go visit LakePontchartain if you ain’t already gone.”

            “On our way there, in fact,” Sherlock said. He narrowed his eyes, apparently attempting to evaluate her intentions. He stood suddenly, shoving his chair out from behind him. “Excuse me.” And he strode off toward the restroom.

            “Are there any legends about it?” John asked. “Famous deaths, or…anything like that?”

            “Oh, I s’pose there’ve been a few, like just about any lake.”

            “It’s an _estuary_ ,” Sherlock called as he opened the restroom door. John rolled his eyes.

            “It’s awful big. I do believe a plane crashed there once.”

            John filed that away, but he supposed it was the sort of thing Sherlock would have already looked up anyway. Still—apparently there were no looming, pervading legends about the lake as a man-eating force of nature. “Thanks,” he said.

            “Now, I’d best get back to the kitchen with your orders,” she smiled and waddled off.

            Several minutes later, Sherlock slid back into his seat.

            “Find anything in the loo, then?” John leaned forward.

            Sherlock winced. “Perhaps too much, but I doubt any of it will be helpful to us. It _has_ been over a week.”

            “Right.”

            When the waitress returned with their food, Sherlock was ready with further questions. “What would you say is your most frequently sold dish?”

            “Oh, the crawfish,” the waitress said. “Some days that’s ‘bout all we sell. Not,” she turned to John, “that the reubens ain’t good. Last I had one, anyhow. But most everybody comes here for the seafood.”

            “Hm,” Sherlock was, perhaps, regretting his decision; if something happened to anyone who ate the crawfish, there likely would have been numerous incidents. “Could I get an order of the chicken as well?” John tilted his head back exasperatedly while the waitress chuckled and strode back from whence she came.

            “Let’s mark this day down in history,” John said. “Sherlock Holmes ordered _two_ meals for himself.”

            “Don’t be an idiot,” Sherlock snorted. “I’m not eating the entirety of either.”

            “Yeah, well, I’ll be ready to save you when you inevitably feel the pull of chanting shrimp from the lake.”

            “It’s an estuary _._ ”

            “Yes, okay, smartarse, now let me eat in peace.”

            Sherlock picked at his crawfish, occasionally taking a bite with the reluctance of a child eating spinach.

            “Not a fan?” John asked.

            “Not hungry,” Sherlock said, and only frowned deeper as his chicken was delivered.

            “Well,” John said, “nobody’s _making_ you eat.”

            “It’s for the _case_ , John.” Sherlock’s nose wrinkled. “You, meanwhile, seem to be rather thoroughly enjoying your…sandwich.”

            “It’s bloody amazing, is why,” John said through a mouthful.

            “I highly doubt it.”

            John gulped down his bite and frowned. “I bet you twenty quid you’re wrong.” He held it out. “Even _you’ll_ like this.” Sherlock simply stared. “Look, okay, fine, ‘back up your claim with scientific evidence,’ how’s that?”

            Sherlock grabbed it and bit into it, chewing slowly as he handed the sandwich back to John. He swallowed. “Awful. You owe me twenty.”

            “You’re just saying that.”

            “The pub two streets from the flat is better.”

            “That one? God, no.”

            “How is everything?” the waitress hovered nearby.

            “Fantastic,” John said, at the same time as Sherlock answered, “Terrible.”

            “Don’t listen to him,” said John. “He’s always like that.”

            When John finished his sandwich not much later, and Sherlock was satisfied with the extent to which he had picked through his two orders to determine that he had tasted nothing unexpected in them, the two paid and headed back to their rented vehicle.

            “So, nothing there,” John summarized.

            “Not much,” Sherlock agreed.

            “I’m surprised you didn’t ask the waitress if she remembered Burroughs and his friends.”

            “She wasn’t working when they came through. Didn’t you see the keychain in her pocket? An atrocious plastic tag reading _California_ , obviously quite new, keys scratch those up quickly; she continually touched the engagement ring on her finger. So, she went to visit her boyfriend in California recently, and got engaged. If she had received the ring and returned by last week, she’d be used to having it on her finger by now.”

            “Right,” John said, and yawned. “Well done, then. Do you think you can handle driving to that motel on your own while I have a bit of a kip?”

            “I suspect I’ll manage.”

            They climbed into the car and a faint rumble drew both their gazes skyward.

            “Looks like storms,” John said.

            “Excellent; perhaps they will simulate the original conditions of the occurrence,” Sherlock grinned, shutting his door as he climbed in. When he turned on the ignition, he also pressed the radio button.

            “What the hell are you doing? I said I was going to nap, didn’t I?”

            “Burroughs and his friends listened to the radio on their trip and heard the advertisement for the estuary.”

            “It’s called _Lake_ Pontchartrain.”

            Sherlock gave an antagonized sigh. “If the program mentions it again, perhaps we can get an idea as to the nature of the advertisement—whether it is somehow sinister, for instance.”

            “You already said you ruled out hypnosis.”

            Sherlock merely sighed again.

 

 

 

            It was only ten minutes later that Sherlock nudged John awake. “They’re playing it,” he said, and John turned the volume up to listen.

            “ _Come down to Lake Pontchartrain,_ ” a charismatic-sounding man was saying, “ _rest for your soul and food for your brain. See everything the water can be—visit our website for further information on fishing, boating, swimming, and more._ ”

            “Seems innocuous enough,” Sherlock shrugged.

            “Mm,” John said, already nodding off again. “Not exactly all horror and demons. I see the crawfish hasn’t made you lose your mind yet.”

            Sherlock snorted, and continued driving to the motel, still some hour and a half away.

Somewhere hour or so later, the storms finally began bubbling up, darkening the sky and rumbling in the distance. Sherlock rolled down the windows, hoping to alleviate the warmth that had built up in the car, and hoped, maybe, a little, that the sound of the whistling of the wind through the cracked windows would wake John, who’d been sleeping like a stone since the first time they’d heard the advertisement for the lake ( _estuary_ ). Not that Sherlock needed John for directions, of course—he’d committed the relevant parts of the map to memory. Still, things were generally better with John conscious, and Sherlock was getting tired of periodically hearing the same advertisement over and over.

            The outside air reeked of ozone, of the nearing of the storm. Sherlock took deep breaths of it, feeling invigorated. Storms, of course, and the symptoms of their coming, always yielded a sense of foreboding, and Sherlock bathed in it. The thunder seemed to crack louder in Louisiana than in London. John wasn’t entirely incorrect when he had suggested Sherlock had taken the case to get away from Mycroft, who had been especially irritating for the preceding several weeks; he had also hoped that John might appreciate being able to forget about work or girlfriends or whatever nonsense was bothering him of late (probably Mycroft, too) and just enjoy solving a case with Sherlock in peace (or as much peace as murder and deadly lakes equated to, which was probably a perfect amount of peace for John Watson anyway).

            There was also the distinct possibility, small though it was, that this would turn out to be something other than some common, dull murder.

            Sherlock squinted at the road. Perhaps—well. No. No, this was definitely the correct exit. Yes, there it was, the Choctaw Motel, the one Burroughs had mentioned parking near to look at the map. There was nothing unusual about the landmark, Sherlock thought, except perhaps the general wariness induced by the oncoming storm. As if on cue, heavy drops began plummeting onto the roof of the car at the thought. They hadn’t entered the motel, of course, just parked near it and looked over the map. Then, according to Burroughs’ tale, a man of questionable origin had approached the vehicle and shouted at them about the lake— _as if the lake had a tongue_ , Burroughs had said.

            There were no such men around here, of course. A party of individuals who had clearly just returned from fishing disembarked from their vehicle; thunder rumbled. Sherlock considered shrugging off his coat, which had remained on his person since before he and John had left England, but then he’d have to climb out of the car, which, for whatever reason, seemed a distinctly unappealing idea.

            So, from here he’d go straight to the lake. The persons in question had gone the route through the woods; the visibility now would be almost as questionable as it was then, but, Sherlock concluded, he could manage it. Of course, the majority of the clues surely resided with the lake itself—perhaps there were bodies buried at its depths. Maybe he could find an article of clothing belonging to one of the friends. Or, perhaps there was some merit to what John had said, and it was all a fanciful story, and there would be nothing to be found there at all—in which case, further interrogation of Burroughs would be required, and perhaps a trip to Missouri, from where they’d left.

            When Sherlock pulled back out of the motel parking lot, John blinked awake. “Can you turn down the bloody radio? ‘S not even playing anything,” he muttered, and fiddled with the dials before apparently giving up. “God, have you been running the heater, Sherlock?”

            “I’ve got the windows down,” Sherlock said, although maybe not for much longer, as the pace of the rain quickened and was soon coming down in buckets, sloshing against the car, pounding the roof almost like hailstones. He rolled them up. “Well, I had done.”

            He began pulling back out to the main road when John sat up stock still in his seat.

            “What is it?”

            John shook his head and blinked. “Nothing, just—did you hear that?”

            “The thunder?”

            “The awful singing,” John said. Sherlock rolled the window back down—oh. The fishing party, apparently rather drunk, had broken into song. John’s tongue darted nervously from his mouth. “Are they singing about th…the lake?”

            Sherlock tried to focus in on the sound, but it was too faint from where they were. It figured that John, exposed to years of gunshots and explosions, would still have better hearing than he had.

            “Jesus _Christ_ ,” John ran one hand through his hair and felt the back of his trousers for his gun, and seemed relieved to find it. Sherlock had arranged to have it shipped separately and picked it up once they arrived—John was always so much more willing to let Sherlock do dangerous things when he knew he’d be able to protect him. John seemed to fumble with the handle, perhaps considering drawing it. “Let’s get _out_ of here, Sherlock.”  
            Spontaneous drunken public singing had always disconcerted Sherlock, too, he supposed, although for how often John went to the pub and came back to 221B singing terribly with Lestrade, _he_ certainly had no right to be upset by it. Sherlock searched for the controls for the windshield wipers and dialed them to the fastest setting to combat the sheets of rain that hit the car almost loudly enough to block out the sounds of the thunder. Lightning flashed around them and John tilted his head back, his voice manic as he pressed, “It’s getting _louder_ , Sherlock, for fuck’s sake, they’re coming _over_ here, can we please just leave?”

            They didn’t _appear_ to be going anywhere, Sherlock thought, but upon closer inspection, maybe they were ambling in their direction, limbs a little stiff, gait a little…inhuman. He shuddered at the same time as thunder cracked. Yes, he thought, fingers twitching with increasing urgency, getting out of here would be a good thing to do. He swerved out into the road and squinted into the windshield to look for the path that the three friends had originally taken on accident, and turned the wheel hard when he almost passed it.

            No _wonder_ they could hardly navigate the place; branches stretched out into the narrow, muddy road like limbs. The dimming light meant that the only time Sherlock was certain of what was ahead of him was when lightning flashed; he shoved his foot onto the gas in the hopes that he could navigate through the place quickly and just be _over_ with it. The lake was what he needed to investigate, anyway. He nearly jumped at the sound of crackling against his windshield until he realized it was the sound of twigs snapping on the car as he swerved close to a row of trees. _God_ , what was wrong with him? It was just a thunderstorm, nothing so awful; still, he felt as if the sounds of the thunder shook his body physically, and the lightning pulled his hair from off his skin. Sherlock pressed harder into the gas and nearly ran into the sign indicating the lake’s proximity. He smashed his foot onto the brake, and the car slid through the wet mud and rotated as it came to a stop just before slamming sideways into a tree.

            “John!” he said breathlessly, “We’re here.” Sherlock shook him by the shoulders; he had fallen back asleep, somehow, in all the madness.

            “ _Christ,_ ” John rubbed his eyes, groaning. Without so much as a word, he unbuckled and swung the door open, nearly falling out of the car. Sherlock stepped out more gracefully (maybe not entirely more gracefully, his muscles aching slightly from the stressful trip through the woods, which was obviously why he felt so numb all over whilst still feeling the prickling of the hairs on his neck) and walked around to John.

            “What was that about?”

            John was rubbing his arms, by all appearances trying to spread the raindrops over them.

            “Well,” Sherlock said, “let’s go.” He nodded toward the shore. “See if we can’t find any articles of clothing, or if anyone who regularly fishes here saw anything.”

            “Yeah,” John said, and then, several seconds later, “Sherlock, I think my arms are on fire.”

            Sherlock’s gaze snapped back to John, and he rotated his body to fully face him. “What was that?”

            “My legs, too. The rain’s not helping.”

            Lightning struck a tree in the woods to Sherlock’s right. Panic struck him simultaneously. When fear etched itself onto Sherlock’s face, John looked down at himself, apparently equally stricken.

            “We should just…” John said, and at the crack of more thunder, flinched. He cleared his throat. “Come on. Let’s go. Let’s…get this over with, and then we’ll worry about…probably…”

            “Yes, good idea,” Sherlock said quietly, and started walking toward the lake. When John was slow to follow, Sherlock returned to him and placed a hand on his back, pushing lightly. “Come on, John.” His voice came out more urgent and strained than he meant it to, or at least more than he thought it would; John’s gaze was fixed elsewhere, entirely unresponsive to Sherlock. With another slight shove, John started walking again.

            He was obviously acting strangely for _some_ reason, Sherlock thought, something that had happened today, maybe, this couldn’t just be tiredness; he tried to process his way through what it might be, and why John hadn’t noticed his own strange behavior yet, but a faint ringing in his ears kept distracting him—well, less a ringing, it was, and more a roaring. Sherlock took a shuddering breath to calm himself.

            “Sherlock!” John barked through the roaring of wind and rain, having stopped suddenly while Sherlock was thinking.

            “What?”

            “Did you hear that?”

            Sherlock squinted in the direction in which John was looking. He could hardly hear _anything_ ; the roaring was nighttime in his ears, masking all other sounds but John’s voice in something akin to the darkness of the landscape as thunderheads shaded it. “What is it?”

            John swallowed. “‘ _Come down to Lake Pontchartrain,_ ’” he mouthed with wide, glazed-over eyes.

            “John, this is _not_ the time,” Sherlock started, but strained his ears to hear it all the same. He could, maybe—it was a little—tinny—but—maybe that was it, maybe that was what John was hearing, _Come down to lake Pontchartrain, come down to Lake Pontchartrain…_ He followed John’s gaze toward the lake, all roiling in the storm, intermittently lit by the lightning, reflecting it like a great mirror to the sky but for the choppy waves that cut through it with the wind.

            John took a stuttered step forward. “You hear it, right?” He looked down at his arms. “I think…I think the lake _knows_ I’m on fire.”

            Sherlock squinted at John.

            He wasn’t joking.

            “John, you absolutely _can’t_ —” Sherlock grabbed him by his sleeve.

            “I need in there, Sherlock,” John said. “It _knows_.” He tugged against Sherlock, rubbed his free hand against his forehead. “Let me go.”

            “Like _hell_ ,” Sherlock hissed, and grabbed John’s arm tighter.

            John fought his way free, struggling like a frightened, snarling dog, and took a few jogging steps backward.

            When Sherlock came toward him again, John drew his gun.

            Sherlock’s chest shook.

The sound of thunder rumbled through him, resonating with his ribcage and extending its quivering. He held his hands up and took a step away from John, who frowned at Sherlock and then set off toward the lake. Sherlock followed distantly, keeping careful watch. Maybe there was _something_ to what John had said; Sherlock felt almost stifled down by a knowing presence. The tinny ringing of the words through his ears further backed up the idea; no one around them was singing. Hell—there _was_ no one around them. “John,” Sherlock finally shouted over the wind as he neared the shore that violently lapped up the edges. “John, _stop_.”

            John shot Sherlock a glare and took a step into the lake.

            He took another, and then another, and before Sherlock could so much as move, John dove in.

            Sherlock lunged after him, but John had a head start, and so Sherlock struggled to catch up to him, swimming as best he could through the vicious and choppy waters. Each of the waves threatened to swallow them both up, and when Sherlock turned back, he could no longer discern the exact location of the shore, waves cutting off his view as if they were trapped in a wide bowl, walls climbing on all sides, and Sherlock wondered, if he breathed too deeply, whether he might swallow some of the water up, and then whether it would swallow him up in retaliation.

            It already was swallowing John.

            Sherlock could see him bobbing there, panicked eyes turned toward Sherlock, as if he were just becoming aware of what had happened, of what he’d done, and Sherlock reached out for him, his great heavy coat dragging him back. John’s fingers wrapped around Sherlock’s, and Sherlock tried to yank him back, back to—to—god—where was the shore, where was the—

            He shouted and coughed, and shouted more, and screamed. “John!”

John’s eyes were glazed over, suddenly, no longer panicking, swiveling around from wave to wave, watching the massive maw of the lake surround them and lap them up, watching the lake’s vicious hunger with dazed interest, unknowing resignation.

            “John!”

            Sherlock’s muscles burned with effort and clenched John’s hand tighter, and pulled him up close, but it didn’t matter so much, did it, what he did, as the sharp gasps that entered his lungs grew smaller and smaller, because this wasit, there was no shore, he and John were going to die here and never be found again, because something had happened to John, because Sherlock had been a berk and let something happen to him. It didn’t matter now, though, so he muttered, “I’m sorry, John, I’m sorry, I’m sorry,” with wet lips, John’s unconscious body held close to his waterlogged coat, and that was it, the shortest gasp, the tiniest gasp, and the waves overtook them, and all Sherlock could feel was the weight of the water and John’s weakening hand.

 

 

 

            John sputtered as brightness filled his vision.

            So _this_ was what it was like to be dead.

            Only, that wasn’t quite right, because of all the things he had assumed about the afterlife, if one were to exist, none of them were _unbearably humid_ or _reeking of fish_ or _awkwardly crusty_.

            Admittedly, he had always half-expected that he’d die alongside Sherlock, so Sherlock’s legs flopped over his, here in this rather unpleasant afterlife, were not particularly surprising.

            From his spot on the ground, John tilted his head to direct his gaze to the ground behind him. There, a ways up the hill, was the car they’d rented, looking maybe a little worse for the wear. What had Sherlock _done_ to it? Little chips in the windshield and scratches in the paint, mud _everywhere._

            Right, the car they had rented, because they were in America—in Louisiana—investigating a case. Something about a guy’s friends being eaten by a lake.

            Oh.

            Right.

            The _lake_.

            That was probably that rather wet thing sloshing against John’s feet. Maybe he wasn’t dead, after all.

            “Sherlock?” he muttered, and shook the man.

            “I’m awake,” Sherlock said quietly. Then, “John, I fear I may have somehow managed to drug you again.”

            “I noticed. Well, not then, of course.”

            “What was it?” Sherlock sat up and rubbed at his temples. “I think I got some too.”

            “Well, we flew in…” John thought, “got our stuff, picked up my gun, talked to the police...drove to the restaurant…ate…and then I fell asleep. Probably the restaurant. Something we ate?”

            “We ate entirely different meals, John, and if they’d had any ingredients in common this sort of thing would have happened to everyone who’s come and gone from the place.”

            “Mm,” John agreed, and closed his eyes and steepled his hands in a rather Sherlockian fashion for several moments before his eyes fluttered open. “ _Oh_.”

            “Oh?”

            “There was one thing we both had—my sandwich.”

            “Right,” Sherlock rolled his eyes. “I had tried to forget.”

            “I said something about being on fire, didn’t I?”

            “Yes.” God, he wouldn’t be forgetting that—the horror, the immediate terror of John, his steady and reliable and usually very lucid John, so obviously removed from himself.

            John sighed, his head rolling back as he sat up as well. “ _St._ _Anthony’s Fire_. Ergotism.”

            “ _Oh._ Yes! The rye bread poisoned us,” Sherlock agreed. “And it poisoned them, too—it was listed on the menu as a side. Or maybe the other waitress fancied them and brought some out for free; it doesn’t matter.” He stood and began pacing. “All three of them had it, but in different amounts, or at different times. Burroughs was lucid enough for most of the drive—like I was—maybe he had less, or maybe he had some leftovers when they pulled over by the motel—but he had _some_ , so he was just suggestible enough to begin believing that the lake was speaking. The man who was the ‘tongue’ of the lake was just a fisherman—asking for directions, or whatever else, who knows. _You_ thought a group of people out singing drunkenly were coming after us.”

            “Yes, thanks, I recall.” And as if John needed _more_ material for traumatic flashbacks. Sherlock was clearly in processing mode; John was still getting over the _alive_ thing. “So did we just sort of…wash up, here?”

            “It would appear so.”

            “So, by sheer luck we happened to be close enough to the shore to wash up before we actually drowned.” John let out a high-pitched laugh. “Figures.” Sherlock smirked. “There is one thing, though, Sherlock,” he paused thoughtfully. “You didn’t have enough to get to the point of feeling like your limbs were burning, did you? If you were only barely affected, why did you come into the lake at all?”

            Sherlock shot John a look of disgust. “Don’t ask such stupid questions, John. I know I call you an idiot, but you needn’t actually live up to the name.” John smiled, and Sherlock cleared his throat. “As I was about to say, the friends, hallucinating a person who was drowning in the lake—or maybe one of them hallucinated it, and the other was suggestible enough to believe it, ran in—fuelled additionally by the side effects of the ergot. They drowned.”

            “Probably.”

            “Almost certainly, or they’d have turned up by now. Burroughs, perhaps out of shock, perhaps succumbing to the effects of the ergot, perhaps both, passed out. By the time he got to the police, neither his blood nor his urine would test positive for any drugs.”

            “But his hair still could,” John’s expression lit up. They began making their way toward the car. “Right—but what about the others? Otherwise we’re just back to him murdering his friends whilst on drugs.”

            “If we can find a receipt for their purchase, or other proof of what they ordered, that should serve as a reasonable piece of evidence to start with, not to mention the general explanatory power of the scenario. Add to that the fact that they will be able to find the ergot-poisoned rye in the restaurant and the general lack of evidence to refute the theory. We could submit our experiences with the matter as support. That should, as they say, seal the deal.”

            “Still, we should stick around to make sure it all goes through.”

            “Why?”

            “Well, for starters, while I’m sure Mycroft will be heartbroken by our extended absence, I _saw_ that you booked that hotel for an entire week.” Sherlock smirked. “There’s no way you actually thought this case would take that long.”

            “Just long enough for you to get over your jet lag.”

            “Get in the car, you stupid git,” John opened Sherlock’s door. “If you really feel like we need to, we can come back tomorrow and see if there’s anything else to be found.”

            “I’d rather not, to be honest,” Sherlock said, and John was temporarily dumbstruck. He glanced out over the wide expanse of the lake, calmed back down now since the passing of the storm last night—how long had they slept? Hours and hours. Well—Sherlock had been awake, so maybe _he_ hadn’t.

            John cleared his throat and spoke quietly. “Sorry for, er…I think I threatened to shoot you.”

            Sherlock took in a slow breath. “Yes. You did do that.”

            “I’m…”

            “It’s fine. It’s…”  
            “No, it’s not fine. What if I would’ve actually done it? I was high as a bloody kite; I could’ve done anything.”

            “But you didn’t. And you wouldn’t.”

            John gave a wry smile. “Let’s hope we never have opportunity to find out otherwise.”

            Sherlock started the car, and the radio clicked on with it; sound blared out: “ _Come down to Lake Pontchartrain…_ ”

            Sherlock and John exchanged horrified glances for half a second before both reached for the dial at the same time, fighting to smash it down, and breaking into shaky laughter.

            “One thing I’m certain of,” Sherlock said as they left the lakefront, the car blessedly quiet, “is that I’m never eating crawfish again.”

**Author's Note:**

> I realize that things such as Hurricane Katrina have happened between the writing of "Lake Pontchartrain" and the timeline of the Sherlock universe, so I've no idea what state it's in now. Also, while I am from the US, I've never been to Louisiana or any nearby areas. 
> 
> The suspect is named after a prep school that one of the band members of Ludo went to.
> 
> All credit for this song goes to Ludo. I hope they don't mind my having played around with it a little bit here. =D If you happen to have discovered this story through a love for Ludo, and also happen to be a Johnlock shipper you may also be interested in my longer fic [The Case of the Moebius Trip](http://archiveofourown.org/works/446714/chapters/764488), which borrows from _Broken Bride_ , or possibly my AU Sherlock [music video to Hum Along](http://youtu.be/suHaSkPZk2k).


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